The present invention relates to a semiconductor device, and more particularly to a semiconductor device having, for example, an AC coupling element.
In order to transmit a signal between semiconductor devices (hereinafter also called “chips”) to which supply voltages different from each other are applied, an AC coupling element formed in the semiconductor device may be used. As the AC coupling element, there have been known an on-chip transformer including a pair of inductors which is magnetically coupled with each other, and a coupling capacitance including a pair of capacitive electrodes which is capacitively coupled with each other. In the present specification, one of the pair of inductors configuring the AC coupling element may be called “first element”, and the other inductor may be called “second element”. Similarly, the pair of capacitive elements may be called “first element” and “second element”.
The first element and the second element configuring the AC coupling element are structured to face each other through an insulating film. When a high voltage is applied between a primary side and a secondary side of the AC coupling element, the high voltage is applied between the first element and the second element. As a result, there is a concern about the deterioration of the insulating film caused by the high voltage, and also insulation breakdown.
Japanese Unexamined Patent Application Publication No. Hei5 (1993)-13543 discloses a configuration in which when a large current flows in a power supply line due to a pin hole or latch-up of the insulating film, a temperature detection unit detects a rise in the chip temperature, and a supply voltage supply unit breaks a current on the basis of a detection signal thereof. U.S. Pat. No. 7,639,021 discloses a configuration in which a voltage of a high voltage battery is measured at given intervals to detect the breakdown of an insulating film. U.S. Pat. No. 8,129,999 discloses a configuration in which the insulation breakdown of a stacked cell is detected on the basis of a current that flows in a shunt resistor connected between a high voltage terminal and a ground terminal of the stacked cell. Shunichi Kaeriyama, Shinichi Uchida, Masayuki Furumiya, Mitsuji Okada, Masayuki Mizuno, “A 2.5 kV isolation 35 kV/μs CMR 250 Mbps 0.13 mA/Mbps Digital Isolator in 0.5 μm CMOS with an on-chip small transformer”, 2010 IEEE Symposium on VLSI Circuits, pp. 197-198, 2010 discloses a configuration of a transmitter circuit and a receiver circuit of an on-chip transformer.